/Engine/Source/Runtime/Engine/Classes/Engine/AssetManager.h
Preloads data for a set of assets in a specific bundle state, and returns a handle you must keep active. These assets are not officially Loaded, so Unload/ChangeBundleState will not affect them and if you release the handle without otherwise loading the assets they will be freed.
Streamable Handle that must be stored to keep the preloaded assets from being freed
virtual [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [FStreamableHandle](API\Runtime\Engine\Engine\FStreamableHandle) > PreloadPrimaryAssets ( const [TArray](API\Runtime\Core\Containers\TArray)< [FPrimaryAssetId](API\Runtime\CoreUObject\UObject\FPrimaryAssetId) > & AssetsToLoad, const [TArray](API\Runtime\Core\Containers\TArray)< [FName](API\Runtime\Core\UObject\FName) > & LoadBundles, bool bLoadRecursive, FStreamableDelegate DelegateToCall, TAsyncLoadPriority Priority )